SpringMongoConverterPerf.java

package ru.yandex.salmon.util.spring.mongo;

import java.lang.reflect.Field;

import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.MongoClient;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.convert.MongoConverter;

/**
 * @author Stepan Koltsov
 */
public class SpringMongoConverterPerf {

    static {
        Thread.setDefaultUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
            @Override
            public void uncaughtException(Thread t, Throwable e) {
                e.printStackTrace();
                // because on-exit hooks may hang
                Runtime.getRuntime().halt(1);
            }
        });
    }

    public static class Foo {
        private final long id;
        private final String payload;

        public Foo(long id, String payload) {
            this.id = id;
            this.payload = payload;
        }

        public long getId() {
            return id;
        }

        public String getPayload() {
            return payload;
        }
    }

    public static void main(String[] args) throws Exception {
        MongoTemplate mongoTemplate = new MongoTemplate(new MongoClient("doesn't matter"), "foobar");
        MongoConverter converter = mongoTemplate.getConverter();

        Field idField = Foo.class.getDeclaredField("id");
        idField.setAccessible(true);
        Field payloadField = Foo.class.getDeclaredField("payload");
        payloadField.setAccessible(true);

        String[] fieldNames = new String[] { "_id", "payload" };
        Field[] fields = new Field[] { idField, payloadField };


        Foo foo = new Foo(10, "data");
        DBObject dbObject = (DBObject) converter.convertToMongoType(foo);

        System.out.println(dbObject);

        for (;;) {
            measure("auto", () -> converter.convertToMongoType(foo));

            //measure("auto back", () -> mongoTemplate.getConverter().read(Foo.class, dbObject));

            measure("hand", () -> {
                try {
                    BasicDBObject r = new BasicDBObject();
                    for (int i = 0; i < fieldNames.length; ++i) {
                        String fieldName = fieldNames[i];
                        Field field = fields[i];
                        r.put(fieldName, field.get(foo));
                    }
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
            });
        }
    }

    private static void measure(String name, Runnable r) {
        long start = System.currentTimeMillis();
        long conversions = 0;
        while (System.currentTimeMillis() - start < 1000) {
            int perIter = 10000;

            for (int i = 0; i < perIter; ++i) {
                r.run();
            }

            conversions += perIter;
        }

        long d = System.currentTimeMillis() - start;
        long dns = d * 1_000_000;

        long nsPerConv = (long) (1.0 * dns / conversions);
        long convPerSecond = 1_000_000_000 / nsPerConv;
        System.out.println("per " + name + ": " + nsPerConv + "ns; " + convPerSecond + "/s");

    }

}